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Weird Problem. No headlights, taillights, or running lights.
Hey guys!
I was left half way stranded last night with no lights. My car is a 2008 C6 Base LS3 MT and I am having a weird problem.
What doesn't work:
Headlights
Taillights
Running lights
Front and Rear side marker lights
High Beams when stalk is pushed forward to stay on position
What does work:
Turn signals front and rear
Brake lights
Highbeams when the stalk is pulled back, once released they shut off again
I checked the common 10A fuse and swapped relays around to see if the lights would come on but no luck. Battery voltage was good but just to be safe I hooked it up to the tender last night.
Took the car out today and still the same issue. I am stumped.
This is difficult to assess........obviously could be a number of things. First, check your battery. All kinds of gremlins show up if the battery is not up to par. In Arizona, the heat kills batteries, and even though mine was tested and the Voltage meter was reading 13v, my battery was causing some gauge glitches, and lights turning on and off etc. Once I replaced the battery, problem solved. My 2007 had the proverbial low beams won't come on problem. Even though the car had the "recall" on that problem done in 2014, it showed up again. I solved the problem with the inside the fuse box jumper wire. Been great since. Here is just one link of many on that issue...
Here are the headlight and exterior lights wiring diagrams. Check for 12v at your HI/LO beam relays: F1/F2/K2/K3. If no voltage is present, you have an underhood fuse block problem. Also reseat the connectors on the BCM. Sometimes passengers press on the floor over the BCM and it causes problems.
2008 LS3 Base A6. I have no helpful input at all... but once I was in the freeway at NIGHT and my headlights went out.
had to use foglights to get back home.
I knew before I got the car that there is a recall for wiring harness burning up for headlights and caused some problems. This happened twice and I took it to the dealer. Couple hours later and 3 years and the car has been great since.
just throwing that out there
This is difficult to assess........obviously could be a number of things. First, check your battery. All kinds of gremlins show up if the battery is not up to par. In Arizona, the heat kills batteries, and even though mine was tested and the Voltage meter was reading 13v, my battery was causing some gauge glitches, and lights turning on and off etc. Once I replaced the battery, problem solved. My 2007 had the proverbial low beams won't come on problem. Even though the car had the "recall" on that problem done in 2014, it showed up again. I solved the problem with the inside the fuse box jumper wire. Been great since. Here is just one link of many on that issue...https://www.youtube.com/watch?v=xSXG01pEIns. Good luck, let us know what you find out!
Here are the headlight and exterior lights wiring diagrams. Check for 12v at your HI/LO beam relays: F1/F2/K2/K3. If no voltage is present, you have an underhood fuse block problem. Also reseat the connectors on the BCM. Sometimes passengers press on the floor over the BCM and it causes problems.
Thank you very much for these and I will check the BCM also. I need to create a kick panel of some sort that doesn't lay right on top of those connectors in the passenger floor board.
Here are the headlight and exterior lights wiring diagrams. Check for 12v at your HI/LO beam relays: F1/F2/K2/K3. If no voltage is present, you have an underhood fuse block problem. Also reseat the connectors on the BCM. Sometimes passengers press on the floor over the BCM and it causes problems.
Just checked and I do have 12V at F1/F2/K2/K3. I have gone and re seated both plugs on BCM as well.
So I tore apart the fuse box and everything looks good.
Some wires have some dark spots but nothing on any of the circuits I am having an issue with. I already replaced the "worst" of the 2 wires and they didn't break apart or anything. It's not an easy task by any means. Installing the new wire is tricky without damaging. I am having to push down hard with a pick or screw driver to get it back into it path and also onto the prongs.
Before doing all this I saw Pin 15 and Pin 3 on the BCM were switching to ground when the headlight switch was put in the "ON" position. This shows that the circuit to the BCM is correct. The relay still wasn't clicking on though. I jumped ground straight to M2 on the underhood fuse box and my headlights came on. I have only really been chasing the headlight issue hoping to find a common location where all these circuits meet. The only location I can find is the BCM and underhood fuse box.
any help is immensely appreciated.
Last edited by Drift Vette; 10-27-2022 at 10:10 PM.
Check the common ground wires for the circuits in question. Sounds like you have lost a grounding point. There are a bunch of them. Search the forum for past postings that show the grounding points and work backwards. Clean each one and ensure they are good and tight.
So it appears there is a LT BLU wire that may be the culprit. It controls the HEADLAMP OFF SWITCH. Which if recall correctly, when you turn the Multi-function switch/turn signal stalk to that position, it will shut all the exterior lights off. Which makes sense with the problem I'm having. The ground circuit for the switch is G201 this couldn't be the problem because there are other parts of the car that ground to this and they function correctly.
I'm wondering if the multi-function switch may have gone bad but it still allows the turn signals and FTP to work. It is also sending out a signal to the BCM whenever I trigger the switch for the headlamps to active. So I know the stalk is doing it job with sending a signal. From the research I have done, when the stalk is activated it sends out a ground signal, at least for the HEADLAMP signal. I am wondering if it is the same for the HEADLAMP OFF Signal and if so, then if I am constantly seeing a ground in that circuit it means the switch is stuck in the off position.
I have attached a schematic below that @PDsVettes sent to me and highlighted the LT BLUE HEADLAMP OFF SIGNAL in red. The other too signal wires for the circuits im having an issue with is highlighted in yellow.
Back probe the LT Blue (pin 17 of C1 on the BCM) with the MFS in the OFF position. You should have a ground. Select any other position and you should lose that ground.
If the above step demonstrates that it is working correctly, try grounding pin H1 of the High Beam Relay and see if your Hi Beams illuminate. Also ground C8 on the Park Lamp Relay to see if your park lamps illuminate.
Do you have a Test Light or Power Probe that you can connect to the battery and check for power or ground by switching the clamps to either post on the battery. If you do, remove the Low Beam Relay and connect your light to M2 and turn the MFS to headlights on. Your test lamp should illuminate if you have a good ground through the BCM. If you don't have one, go to HF and get this or make one with a 12v bulb.
10-08-2022, 08:29 PM
Weird Problem. No headlights, taillights, or running lights.
